N/A.
1. Field of the Invention
This invention relates to emergency position information radio beacons (EPIRBs) that are used to send an emergency signal from a ship or vessel in trouble, seeking help, and in particular to an EPIRB that can interface a global positioning system (GPS) to receive input data (latitude and longitude data) stored in memory in the EPIRB the EPIRB is activated, saving battery power.
2. Description of Related Art
The use of EPIRBs for emergency vessels is well known. Typically an EPIRB is a RF transmitter that transmits R.F. signals on one or more frequencies, normally an emergency band frequency, to notify either surrounding ships, aircraft and even satellites that a vessel is in trouble. EPIRBs can be either manually turned on once an emergency is established or, automatically turned on by contact with the ocean or water, which is self-activating. Also known is the use of a global position system (GPS) that is used with the NAVSTAR system or GLONASS system having satellites that can provide very accurate latitude and longitude geographical positions of location for someone having a GPS receiving device. Typically, three or more satellites in orbit provide triangulation to the hand-held or ship installed unit giving instantaneous and continuous latitude and longitude information.
Although the use of providing an EPIRB with exact current location GPS data in real time would be useful for transmitting a signal during an emergency manually, there are circumstances such as during an emergency wherein the EPIRB would be automatically activated by water (i.e. sinking of the ship) that would be impractical to obtain a current GPS position inputted to the EPIRB because the GPS unit would be physically disengaged from the EPIRB on the sinking ship, or under water. Continuously monitoring the GPS by an activated EPIRB before an emergency would drain the battery of the EPIRB, limiting its usefulness when an emergency occurs.
The present invention overcomes this problem by providing a battery powered EPIRB that can be automatically activated during an emergency by water (or other physical event) while at the same time providing a method and apparatus for storing and maintaining a relatively current GPS input position data within the EPIRB without consuming sufficient continuous battery power that would defeat the purpose of the EPIRB system.
U.S. Pat. No. 5,319,376 issued to Eninger, Jun. 7, 1994 shows an artic submarine buoy and application methods that deploy an EPIRB for use with a global positioning system for a disabled submarine that is trapped under the ice cap to give its position and signal for emergency help. U.S. Pat. No. 5,724,045 issued Mar. 3, 1998 to Kawakami shows a radio transponder that functions as a SART in an emergency condition and as a GPS receiver and VHF transceiver for non-emergency conditions. Neither of these patents show or teach the present invention which allows for periodic GPS input to an EPIRB to reduce battery usage to greatly extend the battery time, prior to EPIRB activation. U.S. Pat. No. 5,355,140, issued Oct. 11, 1994, shows an emergency reporting for marine and airborne vessels that uses GPS and an EPIRB transmitter.
This invention relates to an emergency position information radio beacon (EPIRB) that can be interfaced to receive data from an existing GPS system, before the EPIRB is activated in an emergency. The EPIRB includes a first microprocessor that is continuously powered by the beacon battery at all times, whether the EPIRB is activated or not. The first microprocessor in the EPIRB includes a very low clock rate. Such a clock rate could be 480 khz for low power. The first microprocessor also includes firmware circuitry that provides a sleep mode (almost all of the time) which after a fixed time period, such as ten minutes, wakes up, looks around, loads the new GPS input in position information (latitude and longitude) into the EPIRB memory and then shuts down. This means that the EPIRB unit is power off 99.99 percent of the time, even though every ten minutes, the EPIRB receives location information from the GPS. The result is that the non-activated EPIRB includes position information from a GPS on the vessel that is no older than ten minutes. If an emergency occurs such that the EPIRB is activated by water, meaning that there is an emergency, the memory in the EPIRB contains GPS position data of latitude and longitude that is no older than ten minutes as received by the first microprocessor. At this point during the emergency, once the EPIRB is activated and turned xe2x80x9c00xe2x80x9d, a second microprocessor in the EPIRB is activated and powered by the battery allowing the EPIRB to transmit not only emergency signaling data but also the last stored known latitude and longitude data of the vessel received into the EPIRB memory from the first microprocessor before the EPIRB was activated.
The use of the invention preserves EPIRB battery while at the same time providing positional information that is ten minutes old or less (or other suitable periodic entry) inside the EPIRB. The drawing shows a GPS unit that has a positioning data input interface which could be electrical or optical or any other type of input data that is interfaced to an EPIRB housing that includes the first micro controller attached to the battery. Because of the low clock rate, the first micro controller is powered at all times as to the clock, and every ten minutes for a short period of time loads data in memory from the GPS and then shuts off again. A second micro controller is the part of the EPIRB system that is activated automatically (by a water-activated switch) that turns on the EPIRE unit providing battery power to the entire system, transmitting emergency signals and latitude and longitude information.
Since C/S beacons must operate from a self-contained power source (battery), it is of utmost importance that the GPS interface circuits and EPIRB memory consume negligible amounts of power. The present embodiment of the invention utilizes two micro controllers in a power saving arrangement. The first very low power/low clock rate micro controller receives input data via an electro/optical interface with the GPS and stores the GPS positioning data in the EPIRB memory before activation for subsequent transmission of the emergency signal and the vessel position in an emergency. By use of very low power circuit design and firmware that puts the first micro controller and supporting circuits in a sleep mode for the vast majority of time, power consumption from the battery is reduced to a negligible level while maintaining current GPS data in beacon memory.
The first micro controller is continuously powered by the beacon battery at all times, whether the EPIRB is activated or not.
The second micro controller is used for all EPIRB/beacon control and data processing functions once the beacon is activated in an emergency. It operates at a standard clock rate, typically 16 mhz and at high power to control all beacon functions and internal beacon calculations. The second micro controller is powered only when the beacon has been activated by the emergency such as being immersed in water.
While the two micro controller implementation is preferred, a single micro controller design may be accomplished employing a slightly higher battery power drain.
The method of the invention includes a radio beacon system that has a data input interface with an activated GPS that periodically transfers current GPS geographical data into the EPIRB memory prior to beacon activation. The method also includes using two micro controllers for very low power consumption using sleep firmware to keep power consumption low. The method may also include electro/optical infrared interface (wireless) for improved beacon waterproofing (no input holes in the beacon housing).
In the prior art, the radio beacon was stored in a power-off mode to conserve the battery power but was connected to a GPS positioning data source. Upon activation of the beacon, which would be manually, the GPS data would be transferred to the beacon by an input connection. This situation can work under conditions where there is sufficient time to maintain the connection between the GPS and the EPIRB and the device is manually activated.
However, there are situations for the present invention wherein under an emergency condition the EPIRB could be disconnected from its GPS unit without warning such as fire, capsizing and explosion, in which case the GPS data may not have time to transfer to the beacon after activation and the GPS connection is broken. Under that condition, no GPS position data would be available to be stored in the beacon for transmission to Search and Rescue (SAR) authorities. Using the present invention, the latitude and longitude position from the GPS is stored prior to activation of the EPIRB.
With EPIRBs that have automatic activation, certain types of ships are required to carry beacons that deploy automatically when a ship sinks and submerges the beacon to a depth of up to 4 meters. Prior to reaching the 4 meter depth, the beacon is required to automatically release from the ship and to automatically activate in water. Under these conditions the beacon is under water when it activates and such a condition will certainly disable a connected GPS before position coordinates are transferred to the automatically activated beacon. Under these conditions no GPS position would be stored in the beacon for transmission to SAR authorities. However, using the present invention, with the latitude and longitude stored continuously and periodically within at least ten minutes of the last position of the ship prior to activation of the is beacon, when the EPIRB is activated, it will have in memory the important geographical position information that can be transmitted to third parties giving an almost exact location of where the stranded vessel is located.
It is an object of this invention to provide an improved emergency device especially for marine use which utilizes an EPIRB in combination with a navigational system such as GPS, which greatly extends the useful battery time while still maintaining an update of the EPIRB location from the GPS prior to activation of the EPIRB in an emergency situation.